CN1263411A - Linear three-colour image sensor - Google Patents

Abstract

An improved color image linear sensor is disclosed to minimize the registration problems commonly seen in a sensor using three rows of photodetectors. In particular, according to one embodiment, the photodetectors in the improved color image linear sensor are shaped in triangle so that the triangular-like shaped photodetectors are interspersed with the upside-down triangular-like shaped photodetectors.

Description

Linear three-colour image sensor

The present invention relates to the Image sensing system, more particularly, relate to a kind of linear image sensor with three kinds of color light detectors.

Scanning of image system of many application needs is arranged, so that the one scan object is converted into a kind of electronic form, so that subsequent analysis, printing, distribute and return retaining.Described electronic form generally is exactly an images of described sweep object.An exemplary of scanning of image system is exactly a scanner, and sweep object is exactly one page paper in a book or the one piece of article.By scanner, just produced the electronics or the digital image of this paper.

A scanning of image system generally comprises a sensory package, in order to being an image with a Target Transformation from optics.Described Target Transformation is become that key element is an image sensor the sensory package of an image from optics, it comprises the photodetector of lining up certain array.These photodetectors can respond the light that shines on the described image sensor.Each photodetector all produces electronics (electric charge) signal of a representative from the light intensity of described target reflection, electronic signal from all photodetectors is read out, carry out digitized processing by an analog quantity to digital quantity converter subsequently, with digital signal or the image that produces described target.

In the scanning of image system, it is linear transducer that a kind of image sensor that is used is arranged, and it comprises the triplex row photodetector, is superimposed with the selective transmission filter with each photodetector location on them respectively.Fig. 1 has shown a routine linear image sensor 100, and it comprises three row's photodetectors 102,104,106.Each row front all is equipped with the transmission filter to a certain special spectrum district sensitivity.For example, all photodetectors are superimposed with a Red lightscreening plate respectively, a green color filter and a blue color filter in row number 102,104 and 106.Therefore, when the photodetector in the image sensor 100 is exposed to when being illuminated the one scan object by a white illumination light source, image sensor 100 produces three electronic signals simultaneously.

One of problem that merits attention relevant with image sensor 100 is to need some auxiliary buffer storage and processing procedures to reconfigure electronic signal, so that accurately explain the image pixel of each location.Three corresponding photodetectors were not to navigate on the scanning element physically during each was arranged among three rows, this is because at three row's photodetectors and support respectively due to the gap between the relevant circuit of these photodetectors, therefore must carry out the processing procedure of a pixel location earlier, could use then by the electronic signal of generation or follow-up digital signal.

Constantly the make an effort problem that makes this location of someone reduces to minimum.A kind of method is to reduce by two gaps of arranging between the photodetectors by the size that reduces photodetector, so that each corresponding photodetector can just be located during each was arranged among three rows.Yet the remarkable minimizing of photodetector size can cause the problem of visual sensitivity.Thereby, needing a kind of color image sensor strongly, it does not have orientation problem, and only needs minimum buffer storage and processing procedure, but can export a type and the gratifying color picture signal of quality.

Consider each problem above-mentioned and demand in the development process of the present invention, and be specially adapted to image sensor used in scanner, facsimile machine and the photocopier.By various features described below and advantage, the present invention can be used for the portable scanning device easily.

The scanning of image system all comprises a sensory package usually, makes sweep object convert a kind of image to optical means.Convert sweep object to visual sensory package with optical means, key element wherein is an image sensor.When scanning of image system adopts color image sensor of the present invention, just can dispense the buffer storage and the processing procedure that are used to reconfigure from the electronic signal of each photodetector, thereby can improve sweep speed.In addition, when a black and white sweep object was scanned, because the unique arrangement of the photodetector in this image sensor, the resolution of image had naturally and understandably been turned over one and has been turned over.

According to one aspect of the present invention, disclosed color image sensor comprises row's photodetector, and one at every interval is all triangular in shape in these photodetectors, is clipped in their other photodetectors between per two and then is del.The filter of being made by many single filter elements overlaps on these photodetectors according to the mode of aliging one to one.Therein, these filter elements all have a kind of first spectrum transmitting characteristic every one, are clipped in their other filter elements between per two and then have a kind of in a kind of second spectrum transmitting characteristic and a kind of the 3rd spectrum transmitting characteristic.

The objectives mentioned above and advantage embody by enforcement of the present invention hereinafter described, and produce the embodiment shown in the accompanying drawing.

These and other some features, viewpoint and advantage of the present invention is by being better understood with reference to following description, appending claims and accompanying drawing, wherein:

Fig. 1 has shown an example of the color image sensor that comprises three row's photodetectors;

Fig. 2 A has shown a kind of improved color image sensor according to an embodiment of the invention;

Fig. 2 B has shown the image pixel corresponding to each photodetector of color image sensor shown in Fig. 2 A;

Fig. 3 has shown each chrominance component in the exemplary color pixel of a cover;

Fig. 4 has shown when this image sensor is used to scan a black and white sweep object, how each photodetector has been considered;

Fig. 5 A has shown a width of cloth circuit diagram, and this circuit can be used for reading out in the electronic signal that is produced in each photodetector of the image sensor shown in Fig. 2 A;

Fig. 5 B has shown the one group of control signal that is used for circuit described in Fig. 5 A.

About in the detailed description of the present invention, provide many concrete details hereinafter for thoroughly understanding the present invention.Yet for those of ordinary skill in the art, it is conspicuous not adopting these details also can implement the present invention.Description herein and explanation are experienced or skilled in the art personnel in order most effectively the delivery of content of their work to be given the used common approach of other staff in the art.In other cases, well-known method, process, device and circuit etc. are all introduced in detail, confuse to avoid viewpoint of the present invention unnecessarily mixed up.

One width of cloth chromatic image generally is made up of the image of three width of cloth varying strengths, and they are produced by three main color components that are exposed to a color body respectively.Make and produce one of the way commonly used be exposed to three main color components and be to use a kind of image sensor, it comprises many photodetectors, and the inserted filtering apparatus that on them, superposes, this device is had optionally transmission filter and is formed by many, and align respectively with in the described photodetector each, and make it to form first, second and the strong photodetector of the three or three group selection.With the red, green, blue district in the difference perception visible spectrum.Thereby, have only three components of red, green and blue can pass through these filters, have the image of intensity separately thereby obtain three width of cloth.

Be representatively, these have the image of intensity separately, their numeral of perhaps saying so is more accurately deposited among the form, if with 8 accuracy representings, each width of cloth all is the array or the matrix of its value many pixels (pixel) between 0 to 255, in other words, and each the color pixel C (i in a width of cloth chromatic image, j) all be a vector pixel, and can be represented by the formula: $C\left(\mathrm{ij}\right)=\left[\begin{array}{c}R(i,j)\\ G(i,j)\\ B(i,j)\end{array}\right]$

In the formula, (i be the coordinate of a chromatic image pixel j), and C represents described chromatic image, and R, G, B then represent respectively has three images of intensity separately in chromatic image C.Above-mentioned expression formula also shows, only each strength component R (i, j), G (i, j) and B (i, j) all on time, when promptly they all were from a color body same, a color pixel could be expressed effectively.

If in each width of cloth of three width of cloth monochrome images, the combination S of corresponding image pixel has identical value, be R (i, j)=G (i, j)=(i is j) (wherein when (i is j) within S) for B, on color body, must be achromatization a bit then corresponding to this combination S, visually present certain from black dull to white, otherwise, if in each width of cloth of three width of cloth monochrome images, the combination of these pixels has different values, be R (i, j) ≠ G (i, j) ≠ B (i, j), then on this color body, visually should be colored corresponding to that of this combination S.For example, pure red, pure vector pixel green or pure blue be expressed as respectively C (i, j)=[255,0,0] ^T, C (i, j)=[0,255,0] ^T, or C (i, j)=[0,0,255] ^TCan in a width of cloth chromatic image, reproduce exactly in order to ensure color body, must control meticulously, so that can produce each monochrome image that after combination, can in the chromatic image that is generated, reproduce the various colors of this color body color imaging system.

According to one embodiment of the present of invention, the image sensor that this paper discussed is the array of a straight line, or claims linear transducer.This means that this image sensor once produces delegation's colour signal.The synthetic in order width of cloth chromatic image that just produces of all these colour signals.Under the prerequisite of not losing generality, image sensor as herein described produces the signal of three kinds of colors, i.e. three kinds of monochrome signals of red, green, blue, and each produces by the exposure through a color filtration.

Fig. 2 A has shown the layout plan of a kind of improved image sensor 200 of the invention process.Image sensor 200 is by complementary metal oxide semiconductors (CMOS) (CMOS), or is made by charge-coupled device (CCD), and comprises many leg-of-mutton photodetectors, wherein 20 is labeled as G1 respectively, R2, G3, B4, G5, R6, G7, B8, G9, R10, G11, B12, G13, R14, G15, B16, G17, R18, G19, B20.

As shown in the figure, these leg-of-mutton photodetectors are arranged in such a way, vertical and gap level so that these leg-of-mutton photodetectors are failed between formed color pixel.Or make this gap reach minimum value.More particularly, the triangle photodetector that all that makes progress, G1 for example, G3, G5, G7, G9, G11, G13, G15, the equal coated of G17 and G19 or a kind of transmission filter layer that superposes (below be referred to as the green glow detector) to green (Green) spectral regions sensitivity, and the leg-of-mutton photodetector of all inversions, R2 for example, B4, R6, B8, R10, B12, R14, B16, then alternately coated or stack are with a kind of transmission filter layer (following ruddiness detector and the blue light detector of being referred to as respectively) to red (Red) or blue (Blue) spectral regions sensitivity respectively for R18 and B20, and clearly show in the figure: between these ruddiness detectors and blue light detector, these green glow detectors are alternately interspersing.Also can change a kind of saying, be exactly these inverted leg-of-mutton red or blue light detectors be to be interspersed between per two of these leg-of-mutton green glow detectors.

In addition, here, an inverted triangle is counted as a leg-of-mutton complementary shape.In other words, when general said certain first shape was the complementary shape of certain second shape, that just meaned, with identical first shape of second shape after turn around on the mountain peak, can with second shape amalgamation or the pairing.Fig. 2 B has shown another kind of possible shape, that is, the part of this shape is coupled to well in the corresponding inverted shape and goes.Be noted that: square or circle can not regard complementary as, because it can not cooperate with another square.

Owing to adopted this layout, carrying out delegation's signals sampling from image sensor 200 is according in sequence, and is uniformity, and this point can be found out from Fig. 2 C at an easy rate.The more important thing is that this arrangement makes the interval between two adjacent color pixels of horizontal direction reach minimum, this almost is inaccessiable for normally used square photodetector.So, the problem of common visible image location has just reduced significantly in color image sensor.

In order to represent the vector pixel, Fig. 3 has shown that a color pixel is how to form from the arrangement of this uniqueness, can not bring the problem of pixel location simultaneously again.Understand in conjunction with Fig. 2 A and Fig. 2 C.Table 300 among Fig. 3 has been listed the 10 routine color pixels that produced from the image sensor 200 of Fig. 2 A.Row number 302 has been listed 10 pixel: P1, P2 ..., P10.And in row number 304,306 and 308, shown each pixel green, redness and blue component separately in these color pixels.In this article, this also means: red, green or blue light detector refers to one only to the photodetector of red, green or blue response.

Specifically, representing the one-component of a color pixel from the signal of each green glow detector, red and blue light detector then becomes in two adjacent color pixels separately common component from signal from each.For example, colour phasor pixel P1 and P2 have a green component from two different green glow detectors, but share the same red and blue signal from same red and blue light detector.So, the horizontal clearance between two color pixels just is reduced to minimum, can not cause the loss of picture resolution simultaneously again.In addition, in conjunction with Fig. 2 A, can be easily as seen from Figure 3: according to photodetector, each color pixel clocklike occurs at interval with one, thereby can guarantee to sample uniformly from each photodetector.

Be based on an embodiment using the red, green and blue photodetector as the basis about description of the invention above should be pointed out that.Those of ordinary skill in the art can think that this description can be applied in the occasion of the colored filter of the primary colors that adopts other or complementary colours too.For example, fuchsin, Huang and ultramarine are exactly one group of substituting complementary colours general, that can be used to produce chromatic image.In addition, adopt a cover green glow detector, and alternately to be dispersed in some red and blue light detectors be not requirement of the invention process therebetween, yet, in real life, this but is a kind of preferable embodiment, because human vision system comes more responsively to the color in the green district in a chromatic spectrum than other color.

In many application, usually scan an achromatic object with a color image sensor, perhaps briefly, the object of a black and white of scanning.Certain one page on the textbook for example, and produce (grey or monochromatic) image of a width of cloth black and white.That is a kind of image that only reflects brightness.Photodetector in order to ensure each color can both produce the signal of equal response to the reflection from the black and white scanning object, has adopted the coefficient of a cover weighting to come the different spectral response characteristics of balance from described shades of colour photodetector, and is specific as follows:

KG

1.967KP

5.360KB

Wherein, K is a pondage factor, is set at 1 usually.In other words, can directly indicate on the gray image that is produced, then after suitably amplifying, be indicated on the gray image that is produced from the signal of red and blue light detector from the signal of green glow detector.The result of Chu Liing is like this, and this image sensor has naturally and understandably turned over one to the resolution of black and white scanning object and turned over, and as shown in Figure 4, wherein each photodetector all can produce an image pixel in the brightness image that is produced.

See also Fig. 5 A now, shown a circuit diagram 500 of simplifying among the figure, this circuit is used for reading the signal that image sensor 502 each photodetectors are produced.Image sensor 502 can be corresponding to the image sensor 200 of Fig. 2 A, and comprises many photodetectors that are arranged in a row 503.In order to make orientation problem in the horizontal direction reduce to minimum, the shape of these photodetectors is preferably leg-of-mutton.More particularly, in row triangle photodetector up, alternately be studded with the inverted triangle photodetector of a row exactly, as clearly showing among the figure.

Port Multiplier 504 comprises a plurality of diode switches 508, and each switch 508 all is coupled in each photodetector one get on.Each switch of diode switch 508 is controlled independently by a switching signal.After each photodetector was exposed to a scanning object that is illuminated, a not shown control signal made these photodetectors stop further to gather photon, and the charge signal that is produced is stored among separately the holding capacitor (not shown).Simultaneously, switch 508 closing in sequence.In holding capacitor, sequentially read in the amplifier 511 subsequently from the electronic signal of each photodetector.

This readout is realized by shift register 510.Shift register 510 comprises and the same number of single shift register of photodetector usually.For example, a pulse signal Di feedback is delivered to shift register 510, and Di moves on to another shift register from a shift register by clock signal clk.When a shift register output Di, a corresponding switch in diode switch 508 just is closed (promptly passing through), and a corresponding electronic signal in the holding capacitor of correspondence is just therefrom read.When Di passed through, the electronic signal in each holding capacitor just order shifted out, and carried out the digitlization conversion by an A/D (analog quantity/digital quantity) transducer 512 subsequently.Fig. 5 B has shown a clock signal 520, from wherein being guided out many control signals.S1 among the figure, S2, S3 and S4 are exactly some exemplary control signals (Di of displacement), and they connect 4 switches that link to each other successively.Digital signal 530 from A/D converter 512 outputs is shown among Fig. 5 B.

The present invention has particularity to a certain degree and has been described quite fully.Those of ordinary skill in the art should be appreciated that present disclosed the present invention illustrates by some concrete examples, and do not break away from the spirit and scope of claim of the present invention aspect the permutation and combination of device many variations being arranged.For example, the preferable shape of photodetector is a triangle, and those of ordinary skill in the art may think that the photodetector of other shape also can so design, so that these colourama detectors can more closely be arranged alternately, thereby makes orientation problem reduce to minimum.Therefore, scope of the present invention is limited by every claim, rather than decide by foregoing embodiment.

Claims (18)

1, a kind of color image sensor is characterized in that comprising:

A kind of first type photodetector, it is to the first spectral regions sensitivity;

A kind of second type photodetector, it is to the second spectral regions sensitivity;

A kind of the 3rd type photodetector, it is to the 3rd spectral regions sensitivity;

This photodetector of three types is arranged in a row and arranges by repeat pattern.

2, color image sensor as claimed in claim 1 is characterized in that, described first spectral regions, second spectral regions and the 3rd spectral regions form the colour set that can reproduce the visible most color complementations of human visual system.

3, color image sensor as claimed in claim 2 is characterized in that, described first spectral regions are green, and second spectral regions are red, and the 3rd spectral regions are blue.

4, color image sensor as claimed in claim 1 is characterized in that,

A kind of first transmission filter that described first spectral regions are worked of stack on the described first type photodetector;

A kind of second transmission filter that described second spectral regions are worked of stack on the described second type photodetector;

A kind of the 3rd transmission filter that described the 3rd spectral regions are worked of stack on described the 3rd type photodetector.

5, color image sensor as claimed in claim 4 is characterized in that, is that the described first type photodetector is occurring on the position of a photodetector at least.

6, color image sensor as claimed in claim 5 is characterized in that, the described second and the 3rd type photodetector alternately intersperses among between the described first type photodetector.

7, color image sensor as claimed in claim 1 is characterized in that, each in the described first type photodetector is triangle, and in the described second and the 3rd type photodetector each is complementary triangle.

8, color image sensor as claimed in claim 7 is characterized in that, the described first type photodetector is occurring on the position of a photodetector.

9, color image sensor as claimed in claim 8 is characterized in that, the described second and the 3rd type photodetector alternately intersperses among between the described first type photodetector.

10, a kind of color image sensor comprises:

One row's photodetector, the photodetector every in the described photodetector is a kind of first shape, and the other photodetector every is a kind of second shape;

One filtering apparatus is made up of some single filter elements, and is superimposed upon on described each photodetector with assorting in pairs;

It is characterized in that in described each filter element, all having first spectral-transmission characteristics every one, and other every a filter element all have (1) second spectral-transmission characteristics and

A characteristic in (2) the 3rd spectral-transmission characteristicses.

11, color image sensor as claimed in claim 10 is characterized in that, described first shape and described second shape are complementary, and the gap, location between two adjacent image pixels reaches minimum.

12, color image sensor as claimed in claim 10 is characterized in that, described first shape is a triangle, and described the 3rd shape is an inverted triangle.

13, color image sensor as claimed in claim 12 is characterized in that, described first spectral-transmission characteristics is green, and second the holding property of spectral transmission is red, and the 3rd spectral-transmission characteristics is blue.

14, a kind of color image sensor is characterized in that comprising:

The leg-of-mutton photodetector of one row;

The inverted leg-of-mutton photodetector of one row; And

Described each leg-of-mutton photodetector all is interspersed between two inverted triangle photodetectors.

15, color image sensor as claimed in claim 14 is characterized in that, a kind of filter that first spectral regions are worked of the equal coated of described each leg-of-mutton photodetector; In described inverted triangle photodetector, every an a kind of filter that second spectral regions are worked of equal coated; Other on a described inverted triangle photodetector a kind of filter that the 3rd spectral regions are worked of coated then.

16, color image sensor as claimed in claim 15 is characterized in that, described first spectral regions are corresponding to green; Described second spectral regions are corresponding to redness; Described the 3rd spectral regions are corresponding to blueness.

17, color image sensor as claimed in claim 16 is characterized in that, when being exposed to an achromatic scanning object, each photodetector is all corresponding to a visual image pixel of produce; Wherein, so that the image that is produced vague generalization more, all be subjected to being selected from by K the adjusting of the some factors in the set that 1.967K and 5.360K formed from the signal of each photodetector.

18, color image sensor as claimed in claim 17 is characterized in that, K is set at 1.

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